From: Dominique Martinet dominique.martinet@cea.fr
[ Upstream commit e4ca13f7d075e551dc158df6af18fb412a1dba0a ]
p9_read_work would try to handle an errored req even if it got put to error state by another thread between the lookup (that worked) and the time it had been fully read. The request itself is safe to use because we hold a ref to it from the lookup (for m->rreq, so it was safe to read into the request data buffer until this point), but the req_list has been deleted at the same time status changed, and client_cb already has been called as well, so we should not do either.
Link: http://lkml.kernel.org/r/1539057956-23741-1-git-send-email-asmadeus@codewrec... Signed-off-by: Dominique Martinet dominique.martinet@cea.fr Reported-by: syzbot+2222c34dc40b515f30dc@syzkaller.appspotmail.com Cc: Eric Van Hensbergen ericvh@gmail.com Cc: Latchesar Ionkov lucho@ionkov.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/9p/trans_fd.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-)
diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c index aa4586672cee9..91f71958c2e16 100644 --- a/net/9p/trans_fd.c +++ b/net/9p/trans_fd.c @@ -295,7 +295,6 @@ static void p9_read_work(struct work_struct *work) { int n, err; struct p9_conn *m; - int status = REQ_STATUS_ERROR;
m = container_of(work, struct p9_conn, rq);
@@ -375,11 +374,17 @@ static void p9_read_work(struct work_struct *work) if ((m->req) && (m->rc.offset == m->rc.capacity)) { p9_debug(P9_DEBUG_TRANS, "got new packet\n"); spin_lock(&m->client->lock); - if (m->req->status != REQ_STATUS_ERROR) - status = REQ_STATUS_RCVD; - list_del(&m->req->req_list); - /* update req->status while holding client->lock */ - p9_client_cb(m->client, m->req, status); + if (m->req->status == REQ_STATUS_SENT) { + list_del(&m->req->req_list); + p9_client_cb(m->client, m->req, REQ_STATUS_RCVD); + } else { + spin_unlock(&m->client->lock); + p9_debug(P9_DEBUG_ERROR, + "Request tag %d errored out while we were reading the reply\n", + m->rc.tag); + err = -EIO; + goto error; + } spin_unlock(&m->client->lock); m->rc.sdata = NULL; m->rc.offset = 0;